Re: [dpdk-dev] [PATCH v5] app/testpmd: fix the default RSS key configuration

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 10/20/2020 2:35 PM, oulijun wrote:
> 
> 
> 在 2020/10/20 18:02, Ferruh Yigit 写道:
>> On 10/20/2020 10:00 AM, oulijun wrote:
>>>
>>>
>>> 在 2020/10/16 18:57, Ferruh Yigit 写道:
>>>> On 10/16/2020 11:04 AM, oulijun wrote:
>>>>>
>>>>>
>>>>> 在 2020/10/16 7:53, Ferruh Yigit 写道:
>>>>>> On 10/16/2020 12:21 AM, Ophir Munk wrote:
>>>>>>>> From: Ferruh Yigit <ferruh.yigit@intel.com>
>>>>>>>>>>> On 10/15/2020 1:41 PM, Lijun Ou wrote:
>>>>>>>>>>>> When start the testpmd, the pmd driver initializes the RSS
>>>>>>>>>>>> configuration. Generally, the recommended RSS hash key is used as
>>>>>>>>>>>> the default key in the driver. In addition, the default key is
>>>>>>>>>>>> different from the default RSS flow in testpmd without specifying
>>>>>>>>>>>> RSS hash key. So. if you do not specify the RSS key when creating
>>>>>>>>>>>> an RSS rule, the testpmd uses the default key as the default RSS
>>>>>>>>>>>> key of the RSS rule. As a result, you may mistakenly consider that
>>>>>>>>>>>> the RSS key in use is the valid default key of the NIC, actually,
>>>>>>>>>>>> the key and the valid default key of the NIC are two values.
>>>>>>>>>>>>
>>>>>>>>>>>> Consider the follow usage with testpmd:
>>>>>>>>>>>> 1. first, startup testpmd:
>>>>>>>>>>>> testpmd> show port 0 rss-hash key
>>>>>>>>>>>> RSS functions:
>>>>>>>>>>>>     all ipv4-frag ipv4-other ipv6-frag ipv6-other ip RSS key:
>>>>>>>>>>>> -
>>>>>>>> 6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA3803
>>>>>>>> 0F
>>>>>>>>>>>> -20C6A42B73BBEAC01FA
>>>>>>>>>>>> 2. create a rss rule
>>>>>>>>>>>> testpmd> flow create 0 ingress pattern eth / ipv4 / udp / end
>>>>>>>>>>>> testpmd> actions rss \
>>>>>>>>>>>> types ipv4-udp end queues end / end
>>>>>>>>>>>>
>>>>>>>>>>>> 3. show rss-hash key
>>>>>>>>>>>> testpmd> show port 0 rss-hash key
>>>>>>>>>>>> RSS functions:
>>>>>>>>>>>>     all ipv4-udp udp
>>>>>>>>>>>> RSS key:
>>>>>>>>>>>> -
>>>>>>>> 74657374706D6427732064656661756C74205253532068617368206B65792C
>>>>>>>> 206F
>>>>>>>>>>>> -76657272696465
>>>>>>>>>>>>
>>>>>>>>>>>> In order to solve the above problems, it use the NIC valid default
>>>>>>>>>>>> RSS key instead of the testpmd dummy RSS key in the flow
>>>>>>>>>>>> configuration when the RSS key is not specified in the flow rule.
>>>>>>>>>>>> If the NIC RSS key is invalid, it will use testpmd dummy RSS key as the
>>>>>>>> default key.
>>>>>>>>>>>>
>>>>>>>>>>>> Fixes: ac8d22de2394 ("ethdev: flatten RSS configuration in flow
>>>>>>>>>>>> API")
>>>>>>>>>>>> Cc: stable@dpdk.org
>>>>>>>>>>>>
>>>>>>>>>>>> Signed-off-by: Lijun Ou <oulijun@huawei.com>
>>>>>>>>>>>> Reviewed-by: Phil Yang <phil.yang@arm.com>
>>>>>>>>>>>> ---
>>>>>>>>>>>> V4->V5:
>>>>>>>>>>>> -rewrite the commit log
>>>>>>>>>>>> -add reviewed-by
>>>>>>>>>>>
>>>>>>>>>>> Hi Lijun,
>>>>>>>>>>>
>>>>>>>>>>> There were multiple other comments, it seems they are not addressed
>>>>>>>>>>> but only updated the commit log, can you please check comments to
>>>>>>>> prev versions.
>>>>>>>>>>>
>>>>>>>>>>> Before going into the details, my question was what happens if
>>>>>>>>>>> default key not provided at all?
>>>>>>>>>>> It seems this has been already tried by Ophir [1], later reverted
>>>>>>>>>>> back [2] bringing the initial issue back.
>>>>>>>>>>>
>>>>>>>>>>> According commit, the reason of revert is to support following
>>>>>>>> command:
>>>>>>>>>>> "flow create 0 <pattern> actions rss queues 0 1 end key_len 40 / end"
>>>>>>>>>>>
>>>>>>>>>>> @Ophir, @Lijun,
>>>>>>>>>>> Can we ignore the 'key_len' if the 'key' is not supported and solve
>>>>>>>>>>> current issue as initially intended ([1])?
>>>>>>>>>>>
>>>>>>>>>> Hi, Ferruh
>>>>>>>>>>     I have discussed with Phil Yang about the problem in [1]. I think
>>>>>>>>>> there may be other problems with the idea and there is no better
>>>>>>>>>> solution. and we need to remove key_len definition from rte_rss_conf
>>>>>>>>>> structure. They don't have a plan. And [1] was eventually reverted.
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> Why ignoring 'key_len' (set it to zero) when there is no 'key'
>>>>>>>>> provided doesn't work?
>>>>>>>>>
>>>>>>>>
>>>>>>>> What do you think [1] + following update, will it work?
>>>>>>>>
>>>>>>>>    diff --git a/lib/librte_ethdev/rte_flow.c b/lib/librte_ethdev/rte_flow.c
>>>>>>>>    index ee4f3464fe..e7789c87b3 100644
>>>>>>>>    --- a/lib/librte_ethdev/rte_flow.c
>>>>>>>>    +++ b/lib/librte_ethdev/rte_flow.c
>>>>>>>>    @@ -535,7 +535,7 @@ rte_flow_conv_action_conf(void *buf, const size_t
>>>>>>>> size,
>>>>>>>>                               }),
>>>>>>>>                               size > sizeof(*dst.rss) ? sizeof(*dst.rss) 
>>>>>>>> : size);
>>>>>>>>                    off = sizeof(*dst.rss);
>>>>>>>>    -               if (src.rss->key_len) {
>>>>>>>>    +               if (src.rss->key_len && src.rss->key) {
>>>>>>>>                            off = RTE_ALIGN_CEIL(off, 
>>>>>>>> sizeof(*dst.rss->key));
>>>>>>>>                            tmp = sizeof(*src.rss->key) * src.rss->key_len;
>>>>>>>>                            if (size >= off + tmp)
>>>>>>>>
>>>>>>>
>>>>>>> Ferruh, your suggestion ([1] + update) looks correct. I also verified it 
>>>>>>> on mlx5 PMD.
>>>>>>> Advantage: it's a generic fix for all dpdk applications using rte_flows 
>>>>>>> (not just testpmd).
>>>>>>> It reduces code.
>>>>>>> With this fix the responsibility of handling key==NULL and/or len==0 is 
>>>>>>> moved to the PMDs (which is good).
>>>>>>> With regard to Lijun patch - I liked the approach of overriding the 
>>>>>>> default testpmd key with the default PMD key.
>>>>>>> But it only addresses testpmd. More code was added.
>>>>>>> It seems OK to call rte_eth_dev_rss_hash_conf_get() as part of parsing 
>>>>>>> RSS, but it would feel more confident if we could confirm it for all the 
>>>>>>> PMDs (by testing) or at least review the PMDs rss_hash_conf_get() 
>>>>>>> implementations.
>>>>>>>
>>>>>>
>>>>>> Lijun's idea can work. There was a problem in implementation related to 
>>>>>> the key size assumption, which can be fixed.
>>>>>>
>>>>>> Even it is fixed, when user gives a rss rule without a key, we are getting 
>>>>>> key from device and feeding same key back to device, this is unnecessary I 
>>>>>> think.
>>>>>> When user didn't provide a key, rss rule shouldn't touch the key at all.
>>>>>>
>>>>> Do you mean that the driver should not configure the key to the hardware 
>>>>> when the RSS key is not specified?
>>>>
>>>> We are talking about 'key' in RSS rte flow rule, not generally configuring 
>>>> the device for RSS.
>>>>
>>> Yes, I know. However, I am talking about some implementations. The 
>>> configuration interface may be the same as that for configuring RSS
>>> parameters of the device in general mode.
>>>> If a specific rss rte flow rule, lets say to filter some defined packets to 
>>>> some specific queues, don't have 'key' as a part of rule, I am suggesting 
>>>> not touch 'key' configuration of the device.
>>>>
>>> Yes, I agree. I think your point of view is very reasonable and a more
>>> appropriate implementation. However, for the sake of simplicity and
>>> other considerations in the architecture design of some devices, the
>>> hardware may support reasonable hybrid configuration for paramter 
>>> configuration in the RSS config, rather than independent configuration
>>> for hw, that is, maybe touch A of rss configuration of the device and
>>> must touch B of rss configuration. As a result, If the preceding scenario 
>>> occurs, it is reasonable to configure an RSS config that does not change and 
>>> specified.What do you think?
>>>>> If so, we cannot identify when the user does not specify the RSS key to 
>>>>> determine whether to configure the key.
>>>>
>>>> I think we can. If the rule has 'key' attribute, driver can use that key to 
>>>> program the device, if 'key' attribute is missing, don't do anything related 
>>>> to the rss key.
>>>>
>>> Yes, if 'key' attribute is missing, don't do anything related to the rss key. 
>>> It's more reasonable.
>>> But, If he can't do that, I think it is reasonable to configure the default 
>>> key that already exists on the device. The only disadvantage is wasteful.
>>>>> In hardware design, most vendors do not configure keys for hardware 
>>>>> independently, which may be associated with other RSS config parameters.
>>>>> I think it would be reasonable for us to reconfigure the RSS key with the 
>>>>> default value configured and valid in the hardware as the default value if 
>>>>> the user does not specify the RSS key.
>>>>
>>>> There are already APIs to update the RSS configuration, like RSS key, hash 
>>>> functions etc.. They are independent from the rte flow RSS rule.
>>>> Application should configure RSS according needs using those APIs.
>>>>
>>> Yes, should do this. Are there any unreasonable users who simply do not know 
>>> these APIs or do not want to use them and want to configure some parameters 
>>> through the rte flow RSS rule without changing other parameters?
>>>> The question here is about each RSS rte flow rule that can update the key. 
>>>> Am I missing something?
>>> I don't think you've misunderstood the general situation.
>>> Even if the RSS key is not specified in a rule, the driver uses the default 
>>> key value to re-touch the device.
>>>>
>>>>>> Complication was when user provides key_len without a key, I think both 
>>>>>> ignoring or returning error in this case is OK.
>>>>> I agree. However, I think it is meaningless to expose the RSS key length to 
>>>>> users. Do you consider deleting the RSS key length directly?
>>>>
>>>> Isn't both 'key' and 'key_len' needed to program the RSS key? Can the driver 
>>>> know the size of the 'key' without 'key_len'?
>>>> And driver should verify these provided values.
>>>>
>>> I know and agree.It is only during the analysis of the [1] scheme, from the 
>>> time it was proposed to the time it was withdrawn, that I found some guys in 
>>> the community questioned the significance of key_len.
>>>
>>> Back to the subject, what is your plan for the solution in the patch?
>>
>> I think, Ophir's old reverted patch [1] + 'rte_flow_conv_action_conf()' update 
>> I proposed above can work. Is this working for you? If so can you please send 
>> a patch?
>>
>>
>> [1] https://git.dpdk.org/dpdk/commit/?id=a4391f8bae8
>> .
> Hi, Ferruh
>     I've just used [1] + 'rte_flow_conv_action_conf()' for testing based on the 
> Kunpeng920 NIC plation and use hns3 pmd driver. it can be resolve the RSS key 
> question.
>     testpmd> show port 0 rss-hash key
> RSS functions:
>   all ipv4-frag ipv4-other ipv6-frag ipv6-other ip
> RSS key:
> 6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA
> testpmd> flow create 0 ingress pattern end actions rss func symmetric_toeplitz 
> types all end / end
> 0000:7d:00.0 hns3_config_rss_filter(): modified RSS types based on hardware 
> support, requested:7f83fffc configured:3ef8
> 0000:7d:00.0 hns3_parse_rss_key(): no valid RSS key config, using default
> Flow rule #0 created
> testpmd> show port 0 rss-hash key
> RSS functions:
>   all ipv4-frag ipv4-tcp ipv4-udp ipv4-sctp ipv4-other ipv6-frag ipv6-tcp 
> ipv6-udp ipv6-sctp ipv6-other ip udp tcp sctp
> RSS key:
> 6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA
> 
> However, I also tested the case. I am not specified the RSS key and specified 
> the key_len when create a RSS flow rule, it can create success.
> testpmd> flow create 0 ingress pattern end actions rss queues 0 1 end key_len 40 
> / end
> 0000:7d:00.0 hns3_config_rss_filter(): modified RSS types based on hardware 
> support, requested:a38c configured:2288
> 0000:7d:00.0 hns3_parse_rss_key(): no valid RSS key config, using default
> Flow rule #0 created
> testpmd> show port 0 rss-hash key
> RSS functions:
>   all ipv4-frag ipv4-other ipv6-frag ipv6-other ip
> RSS key:
> 6D5A56DA255B0EC24167253D43A38FB0D0CA2BCBAE7B30B477CB2DA38030F20C6A42B73BBEAC01FA
> 

So are you happy with this solution?